DESCRIPTION (adapted from the Abstract): Over the past decade, heterosexual transmission of HIV has become an increasingly important public health problem. Effective behavioral interventions to increase condom use are needed. Such interventions should be theory-based and capable of being delivered at low cost to large segments of the at-risk population. The proposed study provides an evaluation of the efficacy of an intervention based on the conceptual framework of the Transtheoretic Model. The intervention is designed to increase condom use and readiness to use condoms in at-risk, heterosexually-active women and men. The intervention is computer-delivered using expert systems technology and will be provided in health care settings. Participants will be recruited from four heath clinic sties that serve local ethnic minority communities and will be randomly assigned by a computer to either a stage-matched, individualized expert system intervention, or to an HIV-information comparison group. At the final time point, 400 economically disadvantaged women and men who are at risk for HIV infection will be in the study. Assessment for both groups will be conducted at baseline, 6, 12, and 18 months post-intervention. All participant will receive comparable group-specific intervention materials at baseline, 2 and 4 months. Specifically, participants randomized to the stage-matched treatment group will receive individualized, stage-matched feedback and stage-tailored manuals, and participants randomized to the HIV information comparison group will receive HIV information feedback and the best available informational manual. Incentives for participation and alternative methods for collecting data will be used to maximize participant retention. A secondary aim of the proposed project is to examine additional psychosocial mediators of condom use by testing the predictive efficacy of the Multifaceted Model of HIV risk. An important objective of the study is to increase the understanding of sexual behavior change and to demonstrate the efficacy of a promising intervention technology for increasing condom use. The study will also provide longitudinal outcome data on condom adoption in at-risk heterosexual men and women. Research on innovative approaches to sexual health promotion is central to achieving the Year 2000 goal of reducing HIV transmission and mortality.